1. Field of the Invention
The present invention relates to processes for dewaxing hydrocarbon feedstocks employing zeolite SSZ-54 as a catalyst.
2. State of the Art
Because of their unique sieving characteristics, as well as their catalytic properties, crystalline molecular sieves and zeolites are especially useful in applications such as hydrocarbon conversion, including dewaxing of hydrocarbon feedstocks. Although many different crystalline molecular sieves have been disclosed, there is a continuing need for new zeolites with desirable properties for hydrocarbon and chemical conversions, and other applications. New zeolites may contain novel internal pore architectures, providing enhanced selectivities in these processes.
The present invention is directed to the use of a family of crystalline molecular sieves with unique properties, referred to herein as xe2x80x9czeolite SSZ-54xe2x80x9d or simply xe2x80x9cSSZ-54xe2x80x9d, in dewaxing processes. Preferably, SSZ-54 is obtained in its silicate, aluminosilicate, titanosilicate, vanadosilicate or borosilicate form. The term xe2x80x9csilicatexe2x80x9d refers to a zeolite having a high mole ratio of silicon oxide relative to aluminum oxide, preferably a mole ratio greater than 100, including zeolites composed entirely of silicon oxide. As used herein, the term xe2x80x9caluminosilicatexe2x80x9d refers to a zeolite containing both alumina and silica and the term xe2x80x9cborosilicatexe2x80x9d refers to a zeolite containing oxides of both boron and silicon.
In accordance with the present invention, there is provided a dewaxing process comprising contacting a hydrocarbon feedstock under dewaxing conditions with a catalyst comprising a zeolite having a mole ratio greater than about 20 of an oxide selected from silicon oxide, germanium oxide and mixtures thereof to an oxide selected from aluminum oxide, gallium oxide, iron oxide, boron oxide, titanium oxide, indium oxide, vanadium oxide and mixtures thereof and having, after calcination, the X-ray diffraction pattern of FIG. 1 (i.e., SSZ-54), preferably predominantly in the hydrogen form.
The present invention also includes a process for improving the viscosity index of a dewaxed product of waxy hydrocarbon feeds comprising contacting the waxy hydrocarbon feed under isomerization dewaxing conditions with a catalyst comprising SSZ-54, preferably predominantly in the hydrogen form.
The present invention further includes a process for producing a C20+ lube oil from a C20+ olefin feed comprising isomerizing said olefin feed under isomerization conditions over a catalyst comprising at least one Group VIII metal and SSZ-54. The zeolite may be predominantly in the hydrogen form.
In accordance with this invention, there is also provided a process for catalytically dewaxing a hydrocarbon oil feedstock boiling above about 350xc2x0 F. and containing straight chain and slightly branched chain hydrocarbons comprising contacting said hydrocarbon oil feedstock in the presence of added hydrogen gas at a hydrogen pressure of about 15-3000 psi with a catalyst comprising at least one Group VIII metal and SSZ-54, preferably predominantly in the hydrogen form. The catalyst may be a layered catalyst comprising a first layer comprising at least one Group VIII metal and SSZ-54, and a second layer comprising an aluminosilicate zeolite which is more shape selective than the SSZ-54 of said first layer.
Also included in the present invention is a process for preparing a lubricating oil which comprises hydrocracking in a hydrocracking zone a hydrocarbonaceous feedstock to obtain an effluent comprising a hydrocracked oil, and catalytically dewaxing said effluent comprising hydrocracked oil at a temperature of at least about 400xc2x0 F. and at a pressure of from about 15 psig to about 3000 psig in the presence of added hydrogen gas with a catalyst comprising at least one Group VIII metal and SSZ-54. The zeolite may be predominantly in the hydrogen form.
Further included in this invention is a process for isomerization dewaxing a raffinate comprising contacting said raffinate in the presence of added hydrogen with a catalyst comprising at least one Group VIII metal and SSZ-54. The raffinate may be bright stock, and the SSZ-54 may be predominantly in the hydrogen form.